Foundation and application of Al–Zn–Mg–Cu alloy flow stress constitutive equation in friction screw press die forging

Flow stress behavior of extruded Al–5.7Zn–1.9Mg–1.5Cu alloy bar was studied by thermal compression test with temperature and strain rate ranging from 300 °C to 450 °C and 0.01 s−1 to 10 s−1 respectively. It was founded that the characteristic of flow stress during 350–450 °C can be described by exponential correlation with activate apparent energy of 152 kJ/mol. With the founded constitutive equation, the die forging processing of a connecting rod in friction screw press was simulated with DEFORM-3D software. The optimum preheat temperature of die forging process are 425 °C for billet, and 200 °C for container. The simulation of the hot forming process shows good agreement with experiments results of geometry and streamline of the workpiece.

► Flow stress of Al–Zn–Mg–Cu alloy is studied by thermal compression. ► The obviously different softening rate above and below 350 °C is considered. ► The flow stress constitutive equation is described by exponential correlation above 350 °C. ► With the equation, the die forging processing of a connecting rod was simulated. ► The forming process parameters were optimized by simulation and validated in practice.